A mass \(M\) is attached to a spring system as shown in the figure. If the mass is displaced from its equilibrium position and then released, what is the time period of its oscillation?
1. \(2\pi \sqrt{\dfrac{M}{k}} \) 2. \(2\pi \sqrt{\dfrac{M}{2k}} \)
3. \(2\pi \sqrt{\dfrac{M}{4k}} \) 4. \(2\pi \sqrt{\dfrac{2M}{3k}} \)